/*
* Header file for reservations for dma-buf and ttm
*
* Copyright(C) 2011 Linaro Limited. All rights reserved.
* Copyright (C) 2012-2013 Canonical Ltd
* Copyright (C) 2012 Texas Instruments
*
* Authors:
* Rob Clark <robdclark@gmail.com>
* Maarten Lankhorst <maarten.lankhorst@canonical.com>
* Thomas Hellstrom <thellstrom-at-vmware-dot-com>
*
* Based on bo.c which bears the following copyright notice,
* but is dual licensed:
*
* Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
* USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef _LINUX_RESERVATION_H
#define _LINUX_RESERVATION_H
#include <linux/ww_mutex.h>
#include <linux/dma-fence.h>
#include <linux/slab.h>
#include <linux/seqlock.h>
#include <linux/rcupdate.h>
extern struct ww_class reservation_ww_class;
/**
* struct dma_resv_list - a list of shared fences
* @rcu: for internal use
* @shared_count: table of shared fences
* @shared_max: for growing shared fence table
* @shared: shared fence table
*/
struct dma_resv_list {
struct rcu_head rcu;
u32 shared_count, shared_max;
struct dma_fence __rcu *shared[];
};
/**
* struct dma_resv - a reservation object manages fences for a buffer
* @lock: update side lock
* @seq: sequence count for managing RCU read-side synchronization
* @fence_excl: the exclusive fence, if there is one currently
* @fence: list of current shared fences
*/
struct dma_resv {
struct ww_mutex lock;
struct dma_fence __rcu *fence_excl;
struct dma_resv_list __rcu *fence;
};
#define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base)
#define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
/**
* dma_resv_get_excl - get the reservation object's
* exclusive fence, with update-side lock held
* @obj: the reservation object
*
* Returns the exclusive fence (if any). Does NOT take a
* reference. Writers must hold obj->lock, readers may only
* hold a RCU read side lock.
*
* RETURNS
* The exclusive fence or NULL
*/
static inline struct dma_fence *dma_resv_get_excl(struct dma_resv *obj)
{
return rcu_dereference_protected(obj->fence_excl,
dma_resv_held(obj));
}
/**
* dma_resv_get_list - get the reservation object's
* shared fence list, with update-side lock held
* @obj: the reservation object
*
* Returns the shared fence list. Does NOT take references to
* the fence. The obj->lock must be held.
*/
static inline struct dma_resv_list *dma_resv_get_list(struct dma_resv *obj)
{
return rcu_dereference_protected(obj->fence,
dma_resv_held(obj));
}
/**
* dma_resv_fences - read consistent fence pointers
* @obj: reservation object where we get the fences from
* @excl: pointer for the exclusive fence
* @list: pointer for the shared fence list
*
* Make sure we have a consisten exclusive fence and shared fence list.
* Must be called with rcu read side lock held.
*/
static inline void dma_resv_fences(struct dma_resv *obj,
struct dma_fence **excl,
struct dma_resv_list **list,
u32 *shared_count)
{
do {
*excl = rcu_dereference(obj->fence_excl);
*list = rcu_dereference(obj->fence);
*shared_count = *list ? (*list)->shared_count : 0;
smp_rmb(); /* See dma_resv_add_excl_fence */
} while (rcu_access_pointer(obj->fence_excl) != *excl);
}
/**
* dma_resv_get_excl_rcu - get the reservation object's
* exclusive fence, without lock held.
* @obj: the reservation object
*
* If there is an exclusive fence, this atomically increments it's
* reference count and returns it.
*
* RETURNS
* The exclusive fence or NULL if none
*/
static inline struct dma_fence *dma_resv_get_excl_rcu(struct dma_resv *obj)
{
struct dma_fence *fence;
if (!rcu_access_pointer(obj->fence_excl))
return NULL;
rcu_read_lock();
fence = dma_fence_get_rcu_safe(&obj->fence_excl);
rcu_read_unlock();
return fence;
}
/**
* dma_resv_lock - lock the reservation object
* @obj: the reservation object
* @ctx: the locking context
*
* Locks the reservation object for exclusive access and modification. Note,
* that the lock is only against other writers, readers will run concurrently
* with a writer under RCU. The seqlock is used to notify readers if they
* overlap with a writer.
*
* As the reservation object may be locked by multiple parties in an
* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
* object may be locked by itself by passing NULL as @ctx.
*/
static inline int dma_resv_lock(struct dma_resv *obj,
struct ww_acquire_ctx *ctx)
{
return ww_mutex_lock(&obj->lock, ctx);
}
/**
* dma_resv_lock_interruptible - lock the reservation object
* @obj: the reservation object
* @ctx: the locking context
*
* Locks the reservation object interruptible for exclusive access and
* modification. Note, that the lock is only against other writers, readers
* will run concurrently with a writer under RCU. The seqlock is used to
* notify readers if they overlap with a writer.
*
* As the reservation object may be locked by multiple parties in an
* undefined order, a #ww_acquire_ctx is passed to unwind if a cycle
* is detected. See ww_mutex_lock() and ww_acquire_init(). A reservation
* object may be locked by itself by passing NULL as @ctx.
*/
static inline int dma_resv_lock_interruptible(struct dma_resv *obj,
struct ww_acquire_ctx *ctx)
{
return ww_mutex_lock_interruptible(&obj->lock, ctx);
}
/**
* dma_resv_lock_slow - slowpath lock the reservation object
* @obj: the reservation object
* @ctx: the locking context
*
* Acquires the reservation object after a die case. This function
* will sleep until the lock becomes available. See dma_resv_lock() as
* well.
*/
static inline void dma_resv_lock_slow(struct dma_resv *obj,
struct ww_acquire_ctx *ctx)
{
ww_mutex_lock_slow(&obj->lock, ctx);
}
/**
* dma_resv_lock_slow_interruptible - slowpath lock the reservation
* object, interruptible
* @obj: the reservation object
* @ctx: the locking context
*
* Acquires the reservation object interruptible after a die case. This function
* will sleep until the lock becomes available. See
* dma_resv_lock_interruptible() as well.
*/
static inline int dma_resv_lock_slow_interruptible(struct dma_resv *obj,
struct ww_acquire_ctx *ctx)
{
return ww_mutex_lock_slow_interruptible(&obj->lock, ctx);
}
/**
* dma_resv_trylock - trylock the reservation object
* @obj: the reservation object
*
* Tries to lock the reservation object for exclusive access and modification.
* Note, that the lock is only against other writers, readers will run
* concurrently with a writer under RCU. The seqlock is used to notify readers
* if they overlap with a writer.
*
* Also note that since no context is provided, no deadlock protection is
* possible.
*
* Returns true if the lock was acquired, false otherwise.
*/
static inline bool __must_check dma_resv_trylock(struct dma_resv *obj)
{
return ww_mutex_trylock(&obj->lock);
}
/**
* dma_resv_is_locked - is the reservation object locked
* @obj: the reservation object
*
* Returns true if the mutex is locked, false if unlocked.
*/
static inline bool dma_resv_is_locked(struct dma_resv *obj)
{
return ww_mutex_is_locked(&obj->lock);
}
/**
* dma_resv_locking_ctx - returns the context used to lock the object
* @obj: the reservation object
*
* Returns the context used to lock a reservation object or NULL if no context
* was used or the object is not locked at all.
*/
static inline struct ww_acquire_ctx *dma_resv_locking_ctx(struct dma_resv *obj)
{
return READ_ONCE(obj->lock.ctx);
}
/**
* dma_resv_unlock - unlock the reservation object
* @obj: the reservation object
*
* Unlocks the reservation object following exclusive access.
*/
static inline void dma_resv_unlock(struct dma_resv *obj)
{
#ifdef CONFIG_DEBUG_MUTEXES
/* Test shared fence slot reservation */
if (rcu_access_pointer(obj->fence)) {
struct dma_resv_list *fence = dma_resv_get_list(obj);
fence->shared_max = fence->shared_count;
}
#endif
ww_mutex_unlock(&obj->lock);
}
void dma_resv_init(struct dma_resv *obj);
void dma_resv_fini(struct dma_resv *obj);
int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences);
void dma_resv_add_shared_fence(struct dma_resv *obj, struct dma_fence *fence);
void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence);
int dma_resv_get_fences_rcu(struct dma_resv *obj,
struct dma_fence **pfence_excl,
unsigned *pshared_count,
struct dma_fence ***pshared);
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr,
unsigned long timeout);
bool dma_resv_test_signaled_rcu(struct dma_resv *obj, bool test_all);
#endif /* _LINUX_RESERVATION_H */
